Estimation and Adaptation for Bursty LTE Random Access

With the potential to generate numerous connection requests, an explosive growth in the volume of data traffic and the number of mobile and machine-to-machine (M2M) devices has drawn new attention on the radio access network (RAN). Surging random access attempts cause not only severe preamble collisions but also down-link resource shortage, and thus degrade the performance of random access procedure. However, the effect of down-link resource shortage on system performance is not yet comprehensively studied.

In addition, most existing random access contention resolution mechanisms sacrifice RACH (random access channel) throughput for a high success probability, and thus the price is that low-throughput mechanisms need long time to deal with access attempts. In this work, we evaluate the MAC-level performance for the 4-step random access procedure in LTE systems, for both with and without constrained down-link resources. Further, we propose a novel RACH contention resolution scheme, the dynamic backoff (DB) scheme. DB can achieve high RACH throughput yielding a high random access success probability under various RACH overloaded scenarios.